Thrombus aspiration system and methods for controlling blood loss

ABSTRACT

Aspiration systems and methods for controlling blood loss during thrombus removal are disclosed herein. The systems include an aspiration catheter, an aspiration tubing, a receptacle for collecting aspirated blood, a vacuum line coupled to the receptacle, and a sensor configured to measure a flow parameter associated with a liquid within an aspiration lumen. The systems further include a regulator configured to adjust a vacuum pressure within the vacuum line, and a vacuum controller operably coupled to the sensor and the regulator. The vacuum controller is configured to receive the flow parameter from the sensor, compare the flow parameter to a target range for the flow parameter, and send an automatic control signal to the regulator based on a comparison of the flow parameter to the target range. The automatic control signal causes the regulator to adjust the vacuum pressure within the vacuum line.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application63/180,291, filed Apr. 27, 2021, which is incorporated by referenceherein in its entirety for all purposes.

FIELD

This invention relates to medical devices for thrombus removal, and moreparticularly to thrombus aspiration systems.

BACKGROUND

It is often desirable to remove tissue from the body in a minimallyinvasive manner as possible, so as not to damage other tissues. Forexample, removal of tissue (e.g., blood clots) from the vasculature mayimprove patient conditions and quality of life.

Many vascular system problems stem from insufficient blood flow throughblood vessels. One causes of insufficient or irregular blood flow is ablockage within a blood vessel referred to as a blood clot, or thrombus.Thrombi can occur for many reasons, including after a trauma such assurgery, or due to other causes. For example, a large percentage of themore than 1.2 million heart attacks in the United States are caused byblood clots (thrombi) which form within a coronary artery.

When a thrombus forms, it may effectively stop the flow of blood throughthe zone of formation. If the thrombus extends across the interiordiameter of an artery, it may cut off the flow of blood through theartery. If one of the coronary arteries is 100% thrombosed, the flow ofblood is stopped in that artery, resulting in a shortage of oxygencarrying red blood cells, e.g., to supply the muscle (myocardium) of theheart wall. Such a thrombosis is unnecessary to prevent loss of bloodbut can be undesirably triggered within an artery by damage to thearterial wall from atherosclerotic disease. Thus, the underlying diseaseof atherosclerosis may not cause acute oxygen deficiency (ischemia) butcan trigger acute ischemia via induced thrombosis. Similarly, thrombosisof one of the carotid arteries can lead to stroke because ofinsufficient oxygen supply to vital nerve centers in the cranium. Oxygendeficiency reduces or prohibits muscular activity, can cause chest pain(angina pectoris), and can lead to death of myocardium which permanentlydisables the heart to some extent. If the myocardial cell death isextensive, the heart will be unable to pump sufficient blood to supplythe body's life sustaining needs. The extent of ischemia is affected bymany factors, including the existence of collateral blood vessels andflow which can provide the necessary oxygen.

Clinical data indicates that clot removal may be beneficial or evennecessary to improve outcomes. For example, in the peripheralvasculature, inventions and procedures can reduce the need for anamputation by 80 percent. The ultimate goal of any modality to treatthese conditions of the arterial or venous system is to remove theblockage or restore patency, quickly, safely, and cost effectively. Thismay be achieved by thrombus dissolution, fragmentation, thrombusaspiration or a combination of these methods.

Catheter directed thrombectomy and thrombolysis are commonly perceivedto be less traumatic, less likely to decrease the morbidity andmortality associated with conventional surgical techniques. In recentyears, direct administration of chemical lysing agents into the coronaryarteries has shown to be of some benefit to patients who have thrombosedcoronary arteries. In this procedure, a catheter is placed immediatelyin front of the blockage and a drip of streptokinase is positioned to bedirected at the upstream side of the thrombus. Streptokinase is anenzyme which is able in time to dissolve the fibrin molecule. Thisprocedure can take several hours and is not always successful inbreaking up the thrombus. Furthermore, it can lead to downstreamthrombus fragments (emboli) which can lead to blockage of small diameterbranches.

Thrombectomy is a technique for mechanical removal of blood clots in anartery or vein. It refers to physically removing a clot as opposed toemploying chemical lysis to dissolve it. Multiple devices have beenintroduced to break up and remove clot and plaque, but each has its ownshortcomings. Specifically, the existing systems do not provide adequatemethods for breaking up the clot into smaller pieces for subsequentaspiration. Also, they do not provide a method for removing thethrombectomy device over a guidewire and reinserting into the samelocation to complete the procedure. Furthermore, conventional aspirationsystems offer little control over the amount of blood lost during theprocedure. There is a need for improved thrombectomy devices andaspiration systems that are safer and more effective for removingthrombus and plaque from the vascular system.

SUMMARY

Aspiration systems and methods are disclosed herein for controllingblood loss during thrombus removal. The aspiration systems include, atleast, an aspiration catheter, a thrombus retrieval device extendingthrough the aspiration catheter, and an aspiration tubing fluidicallycoupled to the aspiration catheter. An aspiration lumen extends throughthe aspiration catheter and the aspiration tubing. A sensor measures aflow parameter associated with a liquid within the aspiration lumen. Theaspiration systems further include a receptacle configured to collectliquid aspirated by the aspiration catheter. A vacuum line isfluidically coupled to the receptacle, and a regulator adjusts thevacuum pressure within the vacuum line. A vacuum controller is operablycoupled to the sensor and the regulator. The vacuum controller isconfigured to receive the flow parameter from the sensor, compare theflow parameter to a target range for the flow parameter, and send anautomatic control signal to the regulator based on a comparison of theflow parameter to the target range. The automatic control signal causesthe regulator to adjust the vacuum pressure within the vacuum line.

In some implementations, the automatic control signal causes theregulator to decrease the vacuum pressure upon a determination that theflow parameter is above an upper limit of the target range, and toincrease the vacuum pressure upon a determination that the flowparameter is below a lower limit of the target range. For example, theupper limit can be a flow rate from 70 mL per minute to 130 mL perminute, and the lower limit can be a flow rate from 0 mL per minute to40 mL per minute. In some examples, the vacuum controller is configuredto adjust the flow rate to an intermediate level, such as, for example,from 20 mL per minute to 50 mL per minute. Increases and decreases invacuum pressure can occur in a stepwise manner. In some implementations,the vacuum controller can activate an aspiration program that causesincreases and decreases of vacuum pressure in a stepwise manner. In someexamples, the aspiration program is activated upon receipt ofinformation from one or more manual inputs in communication with theregulator, the vacuum controller, or both.

The receptacle is fluidically coupled to the aspiration tubing, theaspiration catheter, and the vacuum line. In some implementations, anintake port on the receptacle provides the coupling between thereceptacle and the aspiration tubing, and a vacuum port on thereceptacle provides the coupling between the receptacle and the vacuumline. The receptacle can include a receptacle vent in communication withthe regulator or the vacuum controller. The receptacle vent opens uponreceipt of a venting signal from the regulator or vacuum controller.

The aspiration system includes one or more sensors for measuring flowparameters, such as, for example, a flow rate. Some implementations caninclude a plurality of sensors configured to measure one or moreparameters associated with fluid flow at disparate points along a lengthof the aspiration lumen, and to send the measured parameters to thevacuum controller. The sensor may or may not contact the liquid withinthe aspiration lumen.

Some implementations can further include an air leak sensor incommunication with the vacuum controller or the regulator. The air leaksensor can detect air flow through the aspiration tubing and send a leaksignal to the vacuum controller, the regulator, or the vacuum pump upondetection of air through the aspiration tubing. The vacuum controller,regulator, or pump can slow or stop the vacuum flow while the air leakis addressed. In some implementations, the vacuum controller isconfigured to delay detection of air leaks during a vacuuminitialization period. Alternatively, or in addition, the vacuumcontroller can be configured to delay controlling the vacuum in responseto detection of air leaks during a vacuum initialization period.

In some implementations of the system, the regulator adjusts the vacuumpressure within the vacuum line by manipulating a valve that opens thevacuum line to the atmosphere. In some implementations, the regulatoradjusts the vacuum pressure within the vacuum line by manipulating avalve that alters the flow capacity of the vacuum line. The vacuum linecan have a disposable portion and a reusable portion. The disposableportion can be coupled to the reusable portion at a connector. Someimplementations of the system include a vacuum pump. Someimplementations can include a power sensor configured to synchronize thedelivery of power between the pump and the vacuum controller.

The vacuum controller sends signals to one or more components of thesystem to regulate flow of air in the vacuum line and blood through theaspiration lumen. The vacuum controller can be, in some examples, amicroprocessor controller. It can include an analog to digital converterand a digital to analog converter. In some examples, the vacuumcontroller is configured to measure a frequency from the flow parameter.The vacuum controller can operate independently. For example, the vacuumcontroller is capable of operating without input from external sourcessuch as a computer.

Some implementations of the systems include one or more manual inputs incommunication with the vacuum controller, the regulator, and/or areceptacle vent. The manual input is configured to accept a manualcommand and send a first manual control signal responsive to the manualcommand to one or more of the vacuum controller, the regulator, and/orthe receptacle vent. In some examples, upon receipt of the first manualcontrol signal, the vacuum controller stops one or more steps ofcomparing the flow parameter to a target range for the flow parameter,forming an automatic control signal, and/or sending the automaticcontrol signal to the regulator. In some implementations, the vacuumcontroller is configured to send a second manual control signal to theregulator and/or receptacle vent based on the first manual controlsignal. The regulator controls the vacuum pressure within the vacuumline upon receipt of the first manual control signal and/or the secondmanual control signal. The receptacle vent opens or shuts upon receiptof the first manual control signal and/or the second manual controlsignal. Some systems can also include an indicator in communication withthe flow sensor. The indicator is configured to inform a user of acharacteristic of the flow parameter.

In some implementations, at least one braided assembly extends over adistal region of the thrombus retrieval device. The braided assembly caninclude a braid having a shape memory of a collapsed configuration.

In some implementations, the aspiration system further comprises a clampcoupled to the aspiration tubing and a switch operably coupled to theclamp, the switch comprising a closed configuration and an openconfiguration, wherein the switch in the closed configuration causes theclamp to stop fluid flow through the aspiration tubing, and wherein theswitch in the open configuration causes the clamp to allow fluid flowthrough the aspiration tubing. The switch can be in communication withthe vacuum controller and/or the regulator. Shifting the switch to theopen configuration can send a surge protection signal to the regulatorand/or to the vacuum controller. The regulator and/or the vacuumcontroller can reduce the vacuum pressure upon receipt of the surgeprotection signal.

Methods of controlling blood loss during thrombus removal are disclosedherein. The methods include positioning an aspiration catheter withinthe vascular system of a subject and positioning a thrombus retrievaldevice within the vascular system of the subject through the aspirationcatheter. The aspiration catheter is fluidically connected to anaspiration tubing and a vacuum pump. Activation of the vacuum pumpinitiates the flow of blood through the aspiration catheter and theaspiration tubing. A sensor measures a flow parameter of the bloodwithin the aspiration tubing. The flow parameter from the sensor isreceived at a vacuum controller. The flow parameter is compared to atarget range for the flow parameter, and an automatic control signal issent to the regulator based on a comparison of the flow parameter to thetarget range. The vacuum pressure within the vacuum line is adjustedaccording to information stored in the automatic control signal.

In some implementations, the vacuum pump is activated at full power, andadjustments to the vacuum pressure are regulated by the vacuumcontroller while the vacuum pump runs at full power.

The step of adjusting the vacuum pressure can include decreasing thevacuum pressure upon a determination that the flow parameter is above anupper limit of the target range (for example, an upper limit of a flowrate from 70 mL per minute to 130 mL per minute). The step of decreasingthe vacuum pressure can include lowering the vacuum pressure in astepwise manner. In some implementations, the vacuum pressure isdecreased until the measured flow parameter reaches an intermediatelevel flow rate of 20 mL per minute to 50 mL per minute. Some methodsinclude a step of activating an aspiration program upon receipt of amanual command from one or more manual inputs in communication with theregulator and/or the vacuum controller, and the aspiration programincludes lowering the vacuum pressure in a stepwise manner.

The step of adjusting the vacuum pressure can include increasing thevacuum pressure upon a determination that the flow parameter is below alower limit of the target range (for example, a lower limit of a flowrate of from 0 mL per minute to 50 mL per minute). The step ofincreasing the vacuum pressure can include raising the vacuum pressurein a stepwise manner. In some implementations, the vacuum pressure israised until the measured flow parameter reaches an intermediate levelflow rate of 20 mL per minute to 50 mL per minute. Some methods includea step of activating an aspiration program upon receipt of a manualcommand from one or more manual inputs in communication with theregulator and/or the vacuum controller, and the aspiration programincludes raising the vacuum pressure in a stepwise manner.

In some implementations, the step of adjusting the vacuum pressurewithin the vacuum line comprises manipulating a valve that opens thevacuum line to the atmosphere. In some implementations, the step ofadjusting the vacuum pressure within the vacuum line alters the flowcapacity of the vacuum line.

The step of measuring a flow parameter can include measuring a flowrate. Some method implementations use a plurality of sensors to measureone or more flow parameters of the blood at disparate points along thelength of the aspiration lumen. The one or more flow parameters arereceived at the vacuum controller. The methods can further include astep of measuring a frequency from the flow parameter at the vacuumcontroller.

Some method implementations can include a step of detecting air withinthe aspiration tubing and sending a leak signal to the regulator, thepump, or to the vacuum controller. In some implementations, the step ofdetecting air within the aspiration tubing or the step of sending a leaksignal to the regulator or the pump is delayed during initialization ofthe vacuum.

Some method implementations can include a step of accepting a manualcommand at a manual input and sending a first manual control signalresponsive to the manual command to one or more of the vacuumcontroller, the regulator, or a receptacle vent. Upon receipt of thefirst manual control signal, the vacuum controller can stops sendingautomatic control signals to the regulator. In some implementations, asecond manual control signal is formed at the vacuum controller (basedon the first manual control signal) and the second manual control signalis sent to the regulator and/or receptacle vent. Some methodimplementations can include a step of receiving the first manual controlsignal or the second manual control signal at the regulator andcontrolling vacuum pressure within the vacuum line based on the firstmanual control signal or the second manual control signal. Some methodimplementations can include a step of receiving the first manual controlsignal or the second manual control signal at the receptacle vent andopening or shutting the vent based on the first manual control signal orthe second manual control signal.

Some method implementations can include a step of receiving informationfrom the flow sensor at an indicator and informing a user of acharacteristic of the flow parameter using the indicator.

Some method implementations can include a step of shifting a switch froma closed configuration to an open configuration, wherein shifting theswitch to the open configuration causes a clamp coupled to theaspiration tubing to allow fluid flow through the aspiration tubing. Asurge protection signal can be sent upon shifting of the switch to theopen configuration and received at the controller or regulator. Thevacuum pressure can be decreased upon receipt of the surge protectionsignal.

Some method implementations can include a step of synchronizing thedelivery of power between the vacuum pump and the vacuum controller.

DESCRIPTION OF DRAWINGS

The device is explained in even greater detail in the followingdrawings. The drawings are merely exemplary and certain features may beused singularly or in combination with other features. The drawings arenot necessarily drawn to scale.

FIG. 1A is a side section view of an implementation of the thrombectomydevice having a single braided assembly in the collapsed configuration.

FIG. 1B is a side view showing the distal region of the thrombectomydevice carrying the braided assembly of FIG. 1A. The braided assembly isshown in an expanded configuration.

FIG. 1C is a side view showing the distal region of the thrombectomydevice of FIG. 1A. The braided assembly is not included in this view.

FIG. 1D is a cross sectional view of the implementation of FIG. 1A,taken along lines A-A of FIG. 1C.

FIG. 2 shows a side view of an implementation of a handle that can beused to control expansion and retraction of a braided assembly.

FIG. 3A is a side view of a distal region of an additionalimplementation of the thrombectomy device in an unexpandedconfiguration. The implementation has a braided assembly having multiplebraided sections.

FIG. 3B is a side view of the distal region of the implementation ofFIG. 3A in an expanded configuration.

FIG. 3C is a side view of the distal region of the thrombectomy deviceof FIG. 3A. The braided assembly is not included in this view.

FIG. 3D shows a cross sectional view taken along line 3D-3D of FIG. 3C.

FIG. 3E shows a cross sectional view taken along line 3E-3E of FIG. 3C.

FIG. 3F shows a cross sectional view taken along line 3F-3F of FIG. 3C.

FIG. 3G shows a cross sectional view taken along line 3G-3G of FIG. 3C.

FIG. 4 shows an additional implementation of the thrombectomy devicehaving multiple expandable braided assemblies.

FIG. 5A shows a side section view of an implementation of thethrombectomy device that enables use with a guidewire.

FIG. 5B shows the implementation of FIG. 5A in an expandedconfiguration.

FIG. 5C is a cross section of the implementation of FIGS. 5A and 5B,taken along line B-B of FIG. 5B.

FIGS. 6A-6F show an example method of using a thrombectomy device.

FIG. 7A shows a perspective view of another implementation of a handlethat can be used to control expansion and retraction of a braidedassembly.

FIG. 7B shows a bottom up, inside view of the locking slider of thehandle implementation of FIG. 7A.c

FIG. 7C shows a cross section of the locking slider circled in FIG. 7B.

FIG. 8 is a diagram of an aspiration system for controlling blood lossduring thrombus removal.

FIG. 9 is a flow chart of a method for controlling blood loss duringthrombus removal.

FIG. 10 is a line graph depicting a flow rate through an aspirationtubing over time.

FIG. 11 is another line graph depicting a flow rate through anaspiration tubing over time.

FIG. 12 is a diagram of a computing device upon which the disclosedsystems may be implemented.

FIG. 13 shows a proximal end of an aspiration catheter connected via anadapter to an aspiration tubing.

DETAILED DESCRIPTION

The systems and methods disclosed herein aim to reduce the amount ofblood lost during procedures that utilize aspiration to remove thrombusfrom the vasculature. The systems include a vacuum controller for anaspiration pump that is used in conjunction with an aspiration catheterand an aspiration tubing. The aspiration tubing is equipped with a flowsensor in communication with vacuum controller. The vacuum controllermonitors the flow rate of blood being aspirated by the pump andcommunicates with a vacuum regulator to raise the vacuum if the flowrate gets to low (for example, when obstructed by a clot). The vacuumcontroller also communicates with the vacuum regulator to lower thevacuum if the flow rate gets too high. This lowering of the vacuum is asafety feature designed to prevent the system from aspirating bloodinstead of clot. Applying only the vacuum needed to remove the clotprevents unnecessary blood loss. Furthermore, damage to the vasculatureis reduced because the amount of time the system applies full vacuum isminimized. The system can increase or decrease pressure gradually, or ina stepwise manner, to ensure the practitioner has sufficient time torespond to sudden changes in flow rate. The system can also include avariety of manual inputs to slow, pause, or stop the automated flowcontrol processes.

The system disclosed herein integrates flow and vacuum control, usingflow rate to inform the desired vacuum level. Conventional systems donot offer this feature. Many prioritize improving aspiration efficiencyover controlling blood loss. Furthermore, conventional systems oftenadjust vacuum level based on pressure sensors within the aspirationtubing. Because the disclosed system responds specifically to theparameter of interest—the amount of blood flowing through thecatheter—it responds more accurately than pressure measurement-basedsystems. With this system, the user can tune the flow rate, definingminimum and maximum allowed flow rates, and then automate control of thevacuum and flow rate according to those thresholds. This automationreduces the need for the practitioner to monitor and adjust theprocedure for blood loss (though the practitioner is able to overridethe automation when necessary, via the aforementioned manual inputs).Advantageously, the system minimizes the necessary procedure time byoptimizing the aspiration process.

The aspiration system can be used with a variety of catheters and vacuumpumps without changing the core aspiration system. It can be providedwith all of the necessary components, or can be used with componentsthat are provided by the clinician. Furthermore, the vacuum controller,regulator, and pump can be used in the operating theater but fluidicallyisolated from the patient, negating the need for extensivesterilization. Flow manipulation occurs within the vacuum line insteadof the aspiration lumen—a cleaner design than some conventional systemswhere valves directly manipulate blood flow within the aspiration lumen.In the disclosed aspiration systems, components that do contact bloodcan be disposable, whereas fluidically isolated components can bereusable.

The thrombectomy devices disclosed herein remove a thrombus using abraided assembly that can be expanded to a diameter of thepractitioner's choosing, enabling the practitioner to custom fit thedevice to the particular vessel and thrombus and during the procedure.Unlike conventional thrombectomy devices, the diameter of the disclosedbraided assembly can be changed mid-procedure as needed. For example,the braided assembly can be opened to a wider diameter to apply moreoutward force against the thrombus should additional grip be needed forits removal. In some implementations, multiple braided assemblies can beused to address longer thrombi. Each braided assembly can be separatelyexpanded, such that the individual assemblies have different diametersduring the procedure.

The device disclosed herein is used to the remove a thrombus, clot, orplaque from the veins or arteries of the body. It includes an aspirationcatheter and a retrieval device that extends through the lumen of theaspiration catheter. An expandable braided assembly extends over adistal region of the retrieval device, such that when the retrievaldevice exits the distal end of the aspiration catheter, the braidedassembly is positioned outside of the aspiration catheter. An activationwire extends through the lumen of the retrieval device. The distal endof the activation wire exits the retrieval device at an exit point toconnect to and control the expansion of a braided assembly. On theproximal end, the activation wire is attached to a tensioning element.Applying tension to the activation wire causes the braided assembly toexpand to a diameter of the practitioner's choosing. For example, thepractitioner may apply a first level of tension to deploy the braidedassembly to a first, partially expanded configuration and then laterdecide to widen the diameter to the fully expanded configuration byapplying a greater level of tension to the activation wire. The expandedbraided assembly contacts the thrombus, clot, or plaque and is pulledproximally toward the aspiration catheter to assist in removal.Hereinafter the device and methods will be described as removing (orbeing configured to remove) a thrombus. However, it will be understoodthat the device can also be used to remove clots or plaques from thevasculature with no structural (or only slight structural)modifications. Various implementations of the thrombectomy catheterinclude a retrieval device with multiple braided assemblies, multipleactivation wires, multiple braided sections of a single braidedassembly, and retrieval devices with multiple lumens to, for example,enable use with a guidewire.

The following description of certain examples of the inventive conceptsshould not be used to limit the scope of the claims. Other examples,features, aspects, configurations, implementations, and advantages willbecome apparent to those skilled in the art from the followingdescription. As will be realized, the device and/or methods are capableof other different and obvious aspects, all without departing from thespirit of the inventive concepts. Accordingly, the drawings anddescriptions should be regarded as illustrative in nature and notrestrictive.

For purposes of this description, certain advantages and novel featuresof the aspects and configurations of this disclosure are describedherein. The described methods, systems, and apparatus should not beconstrued as limiting in any way. Instead, the present disclosure isdirected toward all novel and nonobvious features and aspects of thevarious disclosed aspects, alone and in various combinations andsub-combinations with one another. The disclosed methods, systems, andapparatus are not limited to any specific aspect, feature, orcombination thereof, nor do the disclosed methods, systems, andapparatus require that any one or more specific advantages be present orproblems be solved.

Although the operations of exemplary aspects of the disclosed method maybe described in a particular, sequential order for convenientpresentation, it should be understood that disclosed aspects canencompass an order of operations other than the particular, sequentialorder disclosed. For example, operations described sequentially may insome cases be rearranged or performed concurrently. Further,descriptions and disclosures provided in association with one particularaspect or implementation are not limited to that aspect orimplementation and may be applied to any aspect or implementationdisclosed. It will understood that various changes and additionalvariations may be made and equivalents may be substituted for elementsthereof without departing from the scope of the invention or theinventive concept thereof. Certain aspects and features of any givenaspect may be translated to other aspects described herein. In addition,many modifications may be made to adapt a particular situation or deviceto the teachings of the invention without departing from the essentialscope thereof. Therefore, it is intended that the invention not belimited to the particular implementations disclosed herein, but that theinvention will include all implementations falling within the scope ofthe appended claims.

Features, integers, characteristics, compounds, chemical moieties, orgroups described in conjunction with a particular aspect, configuration,implementation or example of the invention are to be understood to beapplicable to any other aspect, configuration, implementation, orexample described herein unless incompatible therewith. All of thefeatures disclosed in this specification (including any accompanyingclaims, abstract, and drawings), and/or all of the steps of any methodor process so disclosed, may be combined in any combination, exceptcombinations where at least some of such features and/or steps aremutually exclusive. The invention is not restricted to the details ofany foregoing aspects. The invention extends to any novel one, or anynovel combination, of the features disclosed in this specification(including any accompanying claims, abstract, and drawings), or to anynovel one, or any novel combination, of the steps of any method orprocess so disclosed.

As used in the specification and the appended claims, the singular forms“a,” “an” and “the” include plural referents unless the context clearlydictates otherwise. Ranges may be expressed herein as from “about” oneparticular value, and/or to “about” another particular value. When sucha range is expressed, another aspect includes from the one particularvalue and/or to the other particular value. Similarly, when values areexpressed as approximations, by use of the antecedent “about,” it willbe understood that the particular value forms another aspect. It will befurther understood that the endpoints of each of the ranges aresignificant both in relation to the other endpoint, and independently ofthe other endpoint. The terms “about” and “approximately” are defined asbeing “close to” as understood by one of ordinary skill in the art. Inone non-limiting aspect the terms are defined to be within 10%. Inanother non-limiting aspect, the terms are defined to be within 5%. Instill another non-limiting aspect, the terms are defined to be within1%.

“Optional” or “optionally” means that the subsequently described eventor circumstance may or may not occur, and that the description includesinstances where said event or circumstance occurs and instances where itdoes not.

The terms “coupled,” “connected,” and the like as used herein mean thejoining of two members directly or indirectly to one another. Suchjoining may be stationary (e.g., permanent) or moveable (e.g., removableor releasable). Such joining may be achieved with the two members or thetwo members and any additional intermediate members being integrallyformed as a single unitary body with one another or with the two membersor the two members and any additional intermediate members beingattached to one another.

The terms “proximal” and “distal” as used herein refer to regions of theaspiration tubing or thrombectomy device. “Proximal” means a regionclosest to the practitioner during a procedure, while “distal” means aregion farther from the practitioner during a procedure.

Throughout the description and claims of this specification, the word“comprise” and variations of the word, such as “comprising” and“comprises,” means “including but not limited to,” and is not intendedto exclude, for example, other additives, components, integers or steps.“Exemplary” means “an example of” and is not intended to convey anindication of a preferred or ideal aspect. “Such as” is not used in arestrictive sense, but for explanatory purposes.

A vacuum is a pressure that is less than the local atmospheric pressure.As used herein, “vacuum pressure” indicates the relative pressure, i.e.,the differential between ambient pressure and the absolute pressureapplied by the vacuum. Thus, an increase in relative vacuum pressure isan increase in the difference between ambient pressure and the absolutevacuum pressure, which increases the force applied by the vacuum.Likewise, a decrease in relative vacuum pressure is a decrease in thedifference between ambient pressure and the absolute vacuum pressure,which decreases the force applied by the vacuum.

FIGS. 1A-1D show an implementation of the thrombectomy device 1. FIG. 1Ashows the aspiration catheter 106, the retrieval device 3, a collapsedbraided assembly 102, and a guidewire tip 103. The aspiration catheter106 is an elongated tube with reinforced construction that allows avacuum to be applied at the proximal end to pull clot and emboli out ofthe artery or vein without collapsing. The aspiration catheter 106 canbe formed of a polymer material. The aspiration catheter 106 can includean imaging marker 8 (such as a fluorescent or radiopaque marker) for usein imaging the position of the catheter during a procedure. Thrombusretrieval device 3 extends through aspiration catheter 106. The braidedassembly 102 extends over a distal region 5 of the retrieval device 3,such that when the retrieval device 3 exits the distal end 7 of theaspiration catheter 106, the braided assembly 102 is positioned outsideof the aspiration catheter 106. In the collapsed configuration, braidedassembly 102 is sized and configured for insertion through theaspiration catheter 106 and into an artery or vein. Guidewire tip 103extends distally from the distal end 107 of the retrieval device 3. Theguidewire tip 103 can be flexible, shapeable, and steerable.

The braided assembly 102 is moveable from a collapsed to an expandedconfiguration. An example of a braided assembly 102 in an expandedconfiguration is shown in FIG. 1B, but the maximum diameter, d_(max), ofthe expanded braided assembly 102 can be changed to any value over acontinuous range, from a fully collapsed diameter, to a partiallyexpanded diameter, to a fully expanded diameter. The maximum diameter ofthe braided assembly, d_(max), is the widest point measuredperpendicular to a longitudinal axis, a, extending through the center ofthe braided assembly 102. The braided assembly 102 can be sized andconfigured to disrupt and capture one or more clots, plaques, and/orthrombi and pull them toward the aspiration catheter 106 where they canbe removed. The braided assembly 102 includes a braid 9, a slidablecollar 108, and a fixed attachment point 101 where the braid 9 anchorsto the retrieval device 3. The braid 9 may be attached directly to theretrieval device 3 at attachment point 101, or the braid 9 may beattached indirectly to the retrieval device 3 at attachment point 101.In some implementations, the fixed attachment point 101 is a fixedcollar that extends around the retrieval device 3, and the braid iswelded, bonded, or otherwise adhered to the fixed collar. Regardless, atthe fixed attachment point 101, the braid 9 does not move longitudinallyrelative to the retrieval device 3.

The opposite end of braid 9 is welded, bonded, or otherwise adhered toslidable collar 108. In the implementations shown, the slidable collar108 is slidably connected to the retrieval device 3 by virtue of itsannular shape, which extends circumferentially around the retrievaldevice 3. The slidable collar 108 slides longitudinally along theretrieval device 3 as braid 9 is expanded and collapsed. The slidablecollar 108 can be positioned distally to the fixed attachment point 101(a distal position), as shown in FIGS. 1A-1C, or the slidable collar 108can be positioned proximally to the fixed attachment point 101 (aproximal position). In some implementations, slidable collar 108 orfixed attachment point 101 can include a marker that can be viewed usingimaging modalities during a procedure. For example, the slidable collar108 or fixed attachment point 101 can include a fluorescent orradiopaque label.

The braid 9 is composed of multiple strands of wire. The braid 9 takesan elliptical or a spindle shape when expanded, having a maximumdiameter d_(max) at or near the center of the braid 9 and narrowing asthe braid approaches the fixed attachment point 101 and the slidablecollar 108. The wires are formed of a shape memory material such as, butnot limited to, shape memory polymers or shape memory metals (e.g.,nitinol). The braid 9 has a baseline shape memory of the collapsedconfiguration, which forms a cylindrical structure around the retrievaldevice 3, as shown in FIG. 1A. In the activated, expanded configuration,the braid 9 has a tendency to relax toward the collapsed configuration.

When the practitioner is pulling a thrombus or plaque proximally towardaspiration catheter 106 using braided assembly 102, the braid 9encounters distally oriented drag forces that are strongest along thewidest portions (for example, the central region of the braid adjacentd_(max)) These drag forces resist the proximally oriented pulling forceexerted by the practitioner. The distal end of braid 9 at slidablecollar 108 will encounter less drag force while being pulled proximallybecause the radial force it exerts on the radially adjacent vasculatureor thrombus is small, negligible, or non-existent. If the braid is notproperly designed, the sliding collar 108 and distal end of the braid 9will invert into the wider, central regions of the braid 9. Inversionduring the procedure can be prevented by optimizing factors such as thepic count (crosses per inch), the wire diameter, the number of wires,and the ply of the braid (sets of overlapping braids). Higher pic countsincrease flexibility, while lower pic counts increase longitudinalstiffness. Likewise, a braid with more than one ply (multiple sets ofbraids nested within each other), will be stiffer than a single-plybraid. Braids can be one-ply, two-ply, three-ply, or more. Braids withmore wires will be stiffer than those with fewer wires, and braids withwider diameter wires will be stiffer than those with narrow diameterwires. Wires of varying diameters can be used within the same braid 9.

The design of the braided assemblies 102 disclosed herein may vary basedon whether the device 1 is intended for an arterial procedure or for avenous procedure, since the procedure site will be wider in a venoussetting. For example, a braid 9 designed for a venous application mayhave a d_(max) of from about 0.8 inches to 1.2 inches, including about0.8 inches, about 0.9 inches, about 1.0 inch, about 1.1 inches, andabout 1.2 inches. For venous applications, a braid 9 may have a wirediameter range from about 0.005 inches to about 0.02 inches, including0.005 inches, 0.0075 inches, 0.01 inches, 0.0125 inches, 0.015 inches,0.0175 inches, and 0.02 inches. Different wires of the braid 9 may havedifferent diameters, or they may have the same diameter. In some venousimplementations, the diameters of the wires of the braid 9 are 0.01inches, 0.0125 inches, and/or 0.015 inches. Two-ply braids can utilizesmaller wire diameters without sacrificing the radial force that can beapplied. The pic count can be from 2 to 6 for venous applications. Insome implementations used in venous applications, the pic count is 3, 4,or 5. The number of wires per braid for a venous application can beanywhere from 8 to 40, including 8, 16, 24, 32, and 40.

Braids for venous applications were tested using a selection of theabove listed venous application parameters. End points included theexpansion force and the radial outward force applied by the braid to theinner surface of a tubing that simulates a vein (the tubing having aninner diameter of 24 millimeters). The expansion force is the forcerequired to open the braid, as applied to the activation wire. The datais shown below in Table 1.

TABLE 1 Prototype testing for braids used in venous applications WireMaximum Radial Outward Expansion Braid Diameter # of Braid OD Force in24 mm force Prototype Ply (Inches) Wires (inches) ID tube (N) (N) ADouble 0.008 16 per ply 1.0 4.4 2.5 (32 total) B Double 0.010 16 per ply1.0 5.5-6.6 6 (32 total) C Single 0.0125 24 1.0 8.6-9.9 10

For arterial applications, the braid 9 can have d_(max) of from about0.1 inches to about 0.4, including about 0.1 inches, about 0.12 inches,about 0.14 inches, about 0.18 inches, about 0.2 inches, about 0.22inches, about 0.24 inches, about 0.28 inches, about 0.3 inches, about0.32 inches, about 0.34 inches, about 0.36 inches, about 0.38 inches andabout 0.4 inches. For example, the braid 9 can have a d_(max) of about0.28 inches, 0.3 inches, or 0.31 inches. The diameter of the wires ofthe braid 9 for an arterial application can range from about 0.001inches to about 0.007 inches, including about 0.001 inches, about 0.002inches, about 0.003 inches, about 0.004 inches, about 0.005 inches,about 0.006 inches, and about 0.007 inches. Different wires of the braid9 may have different diameters, or they may have the same diameter. Insome arterial implementations, the diameters of the wires of braid 9 are0.003 inches, 0.004 inches and/or 0.005 inches. Two-ply braids canutilize smaller wire diameters without sacrificing the radial force thatcan be applied. The pic count can be from 5 to 30 for arterialapplications, including a pic count of 5, 6, 7, 8, 9, 10, 11, 12, 13,14, 15, 16, 117, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 and 30.In some implementations used in arterial applications, the pic count is10, 12, or 15. The number of wires per braid 9 for an arterialapplication can be anywhere from 8 to 54, including 8, 16, 24, 32, 40,48, and 54. In some implementations, the number of wires per braid 9 foran arterial application is 26, 24, or 30.

Braids for arterial applications were tested using a selection of theabove listed arterial application parameters. End points included theradial outward force applied by the braid to the inner surface of atubing (the tubing having an inner diameter of 6 millimeters), and theproximal force needed to pull the braid through a restriction in thetubing (the inner diameter of the restriction being 4 millimeters). Thetubing and the restriction simulate an artery and a thrombus/plaque,respectively. Favorable prototypes give a high radial outward forcewithout requiring excessive force to pull the braid through therestriction. The data is shown below in Table 2. All braids tested wereone-ply.

TABLE 2 Prototype testing for braids used in arterial applicationsRadial Force to pull Profile Outward through (Distal Force applied 4 mmWire bond Maximum to 6 mm I.D. ID Diameter Pic # of OD) Braid OD tubingRestriction Prototype (inches) count Wires (inches) (inches) (Newtons)(Newtons) A 0.004 10 16 0.050 0.28 0.8 1.8 B 0.004 15 24 0.053 0.28 1.02.8 C 0.005 10 16 0.054 0.31 1.5 3.2 D 0.005 10 24 0.058 0.31 1.6 4.1 E0.006 10 16 0.060 0.31 1.7 4.4 F 0.006 12 16 0.063 0.30 1.8 4.6 G 0.00224 48 0.073 0.31 0.8 1.9 H 0.003 24 48 0.078 0.31 1.8 3.5 I 0.004 12 240.054 0.31 1.9 2.6

The activation wire 105 extends through the lumen of the retrievaldevice 3, exits the retrieval device 3 at exit point 11, and extendsdistally along the exterior surface of the retrieval device 3. Thedistal end 13 of the activation wire 105 is attached to slidable collar108. As such, the activation wire 105 is able to control the expansionand collapse of the braid 9 via the slidable collar 108. The distancebetween exit point 11 and slidable collar 108 affects the length thatthe slidable collar can be pulled along retrieval device 3 to open thebraided assembly 102. If it is too close to slidable collar, the braidedassembly 102 will not be able to open fully. As such, exit point 11should be positioned proximally far enough from the unexpanded positionof slidable collar 108 to enable the braided assembly 102 to open to itsmaximum outer diameter. FIG. 1C shows the implementation of FIGS. 1A and1B without braid 9 to facilitate viewing the activation wire 105 and theactivation wire exit point 11. FIG. 1D is a cross sectional view ofactivation wire 105 in retrieval device 3, taken at line A-A of FIG. 1C.The internal positioning of the proximal regions of the activation wire105 (within retrieval device 3) is advantageous in that no friction orbulk is added by the system that controls expansion of the braidedassembly 102.

The proximal region of activation wire 105 (not shown) may be tensionedand released to control the expansion and collapse of the braidedassembly 102 via movement of slidable collar 108. Under tension, theactivation wire 105 moves proximally within the lumen of the retrievaldevice 3 as it translates the tension from the proximal region of theactivation wire 105 to the braided assembly 102. In implementationswhere the slidable collar 108 is in the distal position (as shown), theexit point 11 of the activation wire is located proximally to theslidable collar 108. The exit point 11 can be, for example, a portal inthe sidewall of retrieval device 3. Use of a slidable collar 108 toexpand the braided assembly 102 is advantageous because the distal endof the braided assembly 102 can be moved while the distal region 5 ofthe retrieval device 3 maintains a constant position within thevasculature. Maintaining a constant position of the distal region 5 ofretrieval device 3 is advantageous because sliding proximal/distalmovement of the distal region 5 within the vessel can result in vesseldamage or perforation.

In implementations where the slidable collar 108 is in the proximalposition relative to the fixed attachment point (not shown), theactivation wire 105 extends distally past the slidable collar 108 insidethe retrieval device 3, exits the retrieval device 3 at exit point 11,then doubles back and extends along the exterior surface of theretrieval device 3 to attach to the proximally located slidable collar108. The exit point 11 can be a portal in the sidewall of the retrievaldevice as described above, or the exit point 11 can be the distal end107 of the retrieval device 3.

Retrieval device 3 can include a proximal hypotube 100 and a distalsupport tube 104, as shown in FIG. 1C. In some implementations, thehypotube 100 extends through the support tube 104. However, the distalregion can be made more flexible by attaching the proximal end of thedistal support tube 104 to the distal end 17 of the proximal hypotube100 (for example, by adhesive bonding, heat bonding, or weldingprocesses). The fixed attachment point 101 of the braided assembly 102can be located on distal support tube 104 and the slidable collar 108can extend around the distal support tube 104, such that the braidedassembly 102 is positioned over and around the distal support tube 104.The braided assembly 102 can alternatively be positioned only partiallyover the distal support tube (i.e., one of the fixed attachment point101 or the slidable collar 108 is attached to the proximal hypotube 100,and the other of the fixed attachment point or the slidable collar 108is attached to the distal support tube 104). In some implementations,the support tube 104 serves to increase the overall diameter of theretrieval device 3, for example, to accommodate a larger diameter braidand to encapsulate the guidewire tip 103. The distal support tube 104can also provide a lower friction surface for movement of the slidablecollar 108 than the proximal hypotube 100 would provide.

In some implementations, distal support tube 104 has greater flexibilitythan the proximal hypotube 100. For example, the distal support tube 104can be made of a polymer material, while the proximal hypotube 100 ismade of a more rigid metal material. In some implementations, theproximal hypotube 100 is constructed from metal hypodermic needletubing. The hypotube 100 can be up to 50 times stiffer than the supporttube 104. There are several advantages to having a distal support tube104 with greater flexibility than proximal hypotube 100. The greaterflexibility of the support tube 104 enables a gradual transition inflexibility between the hypotube 100 and the guidewire tip 103. In somescenarios, the greater flexibility of the distal support tube 104 canfacilitate movement of the braided assembly 102 through a tortuousthrombus. The greater flexibility can promote kink resistance. Thegreater flexibility of the distal support tube 104 can also facilitatethe introduction of a portal or exit point 11 during the production ofthe device. The higher rigidity of the hypotube 100 (as compared tosupport tube 104) is important because it allows the retrieval device 3to be pushed through the vasculature. The rigidity of hypotube 100 alsohelps to ensure that the braided assembly 102 can be pushed through athrombus or plaque.

On the proximal end, the activation wire 105 can be attached to atensioning element (not shown) that allows the activation wire 105 to bemoved forward or retracted backward within the retrieval device 3.Applying tension to the activation wire 105 causes the slidable collar108 to move and causes the braided assembly 102 to expand to a diameterof the practitioner's choosing. Similarly, releasing tension on theactivation wire 105 allows the braided assembly 102 to relax into thecollapsed, baseline configuration.

In some implementations, such as the one shown in FIG. 2, the deviceincludes a proximal handle 128. The handle 128 is coupled to a proximalend of retrieval device 3. The tensioning element is a knob 129 that iscoupled to the proximal end of activation wire 105 on the inside of thehandle. Actuation of the knob 129 in one direction causes the activationwire 105 to be tensioned (expanding the braided assembly), and actuationof the knob 129 in the opposite direction releases tension on theactivation wire 105 (collapsing the braided assembly). In otherimplementations, the tensioning element can include a slider, ratchetingmechanism, or lever.

In some implementations, aspiration catheter 106 terminates in anadapter, such as adapter 204 shown in FIG. 13. The adapter 204facilitates the connection of aspiration tubing 203, which can beconnected to a vacuum system such as shown in FIG. 8 for removal of theclot or emboli. In some exemplary procedures, the distal end ofretrieval device 3 is inserted axially through into the proximal end ofadapter 204 (where shown using the arrow in FIG. 13). The retrievaldevice 3 is slid through the adapter 204 and subsequently through theaspiration catheter 106 until handle 128 abuts the proximal end ofadapter 204.

Another implementation of a proximal handle 128 is shown in FIGS. 7A-7C.The handle 128 of FIGS. 7A-7C is advantageous in that it enables apractitioner to lock the braided assembly 102 at a fixed outer diameter.This can be useful, for example, when pushing and pulling the devicethrough a thrombus. As shown in FIG. 7A, proximal handle 128 is coupledto a proximal end of retrieval device 3. Activation wire 105 extendsproximally past the proximal end retrieval device 3 and into proximalhandle 128. Strain relief section 139 is formed of a flexible materialthat prevents kinking of the retrieval device 3 just distal to thehandle 128. Proximal handle 128 also includes a tensioning element inthe form of locking slider 136, which slides proximally and distallywithin groove 138 and can be locked in place to secure the outerdiameter of the braided assembly 102 during a procedure. The undersideof locking slider 136 and groove 138 is shown in FIG. 7B, and a crosssectional view of locking slider and groove 138 is shown in FIG. 7C.Locking slider 136 includes a sliding portion 146 and a lock button 148.As seen in FIG. 7B, downward pointing teeth 140 extend downward from theinner surface 133 of the outer casing 135 of handle 128, from a positionadjacent the groove 138. The lock button 148 includes an exteriorportion 141 with a textured gripping surface. The lock button 148extends downward through sliding portion 146, and includes an interiorportion 137. The interior portion 137 of the lock button 148 extendsaway from the exterior portion 141 of lock button 148 in a directionthat is perpendicular to the longitudinal axis A-A of the locking slider136. Interior portion 137 includes upward facing teeth 142 that areconfigured to engage with the downward facing teeth 140 of the outercasing 135 of the handle 136. Spring 150, which is vertically positionedwithin slider 146, beneath the exterior surface 141 of lock button 148,exerts an upward force on lock button 148 to hold the upward facingteeth 142 in a locked configuration with the downward facing teeth 140of the outer casing 135. When lock button 148 is compressed, the spring150 is compressed and the teeth 140, 142 disengage. With the lock button148 pressed and the teeth 140, 142 disengaged, proximal or distal forcecan be applied to sliding portion 146 to move the locking slider 136within the groove 138. An interior portion 144 of the sliding portion146 grips the activation wire 105. As the locking slider 136 is movedwithin groove 138, the activation wire 105 is moved proximally ordistally to affect the expansion or allow the collapse of the braidedassembly 102.

Conventional thrombectomy devices utilize shape memory elements with abaseline expanded configuration. These conventional devices riskinadvertent overexpansion and damage to the vessel. Furthermore,conventional devices are often restrained by a bulky overlying sheath,which is pulled back to allow the device to self-expand.

Advantageously, using a device with a shape memory of the collapsedposition reduces the risk of overexpansion and injury duringself-expansion. Self-collapse also allows the device to be restrainedusing the low-profile activation wire system described herein. Anadditional advantage is the ability to expand the braided assembly tovarious diameters to precisely custom fit the size of the vessel. Thiscan be especially useful if the size of the vessel is different thanoriginally anticipated. The level of grip between the braid 9 and thesurrounding thrombus can also be customized as needed by applyingdifferent levels of tension to the activation wire 105. For example, thepractitioner may apply a first level of tension to deploy the braidedassembly 102 to a first expanded outer diameter to contact the thrombus.If the force between the thrombus and the braid 9 is not enough to pullthe thrombus toward the aspiration catheter 106, the practitioner canwiden the braid 9 to a second expanded outer diameter by applying agreater second level of tension to the activation wire 105. This wideneddiameter provides a greater contact force between the thrombus and thebraid 9, such that the thrombus can be more easily pulled towardaspiration catheter 106.

FIGS. 3A-3D show an additional implementation of a thrombectomy devicehaving a braided assembly 19 with multiple braided sections 111, 112.The elongated nature of this implementation facilitates the capture andretrieval of long thrombi. As shown in FIG. 3A and FIG. 3B, ach of thebraided sections 111, 112 is attached to and extends around the distalregion 22 of retrieval device 21. The braided assembly 19 includesmultiple sliding collars 23, 25 and a fixed attachment point 27.Proximal braided section 111 is attached to and extends between thefixed attachment point 27 and the proximal slidable collar 23, where itis welded, bonded, or otherwise adhered at a central sliding attachmentpoint 29. Distal braided section 112 is attached to and extends betweenthe proximal slidable collar 23 and the distal slidable collar 25. Insome implementations, the braided sections are formed by constrainingone larger braid with the proximal slidable collar 23. In otherimplementations, each braided section is formed from a separate braid(such that each of the proximal and distal braided assemblies areseparately fixedly attached to proximal slidable collar 23). In someimplementations, the slidable collars 23, 25 can be positioned distallyto the fixed attachment point 27, as illustrated in FIG. 3A. In otherimplementations, the slidable collars can be positioned proximally tothe fixed attachment point (not shown). Though illustrated with twobraided sections 111, 112, other implementations of the braided assembly19 could include more than two braided sections and more than twoslidable collars.

FIG. 3C shows the thrombectomy device of FIGS. 3A and 3B without thebraided assembly 19. Retrieval device 21 has a hypotube 131 fixedlyattached to a support tube 130. A single activation wire 132 extendsthrough hypotube 131 and support tube 130 to an exit point 134positioned on the support tube 130. From there, it travels along theouter surface of support tube 130, running beneath proximal slidingcollar 23 to attach to distal sliding collar 25. Cross sectional viewsshown in FIG. 3D, FIG. 3E, FIG. 3F, and FIG. 3G show the radial positionof activation wire 132 with respect to hypotube 131, the support tube130, and the guidewire tip 103 at various axial locations along thethrombectomy device shown in FIG. 3C. The activation wire 132 isutilized to control expansion of the braided assembly via connection tothe distal sliding collar 25. In other implementations, the activationwire 132 can be attached to the proximal sliding collar 23. Proximalmovement of the proximal slidable collar 23 or the distal slidablecollar 25 by the activation wire generates a force on the other of thetwo slidable collars, such that the two braided sections 111, 112 areexpanded (or partially expanded) in unison. As described above, thebraids are formed of a shape memory material with a bias toward thecollapsed configuration, so that tensioning the activation wire enablesmultiple levels of expansion.

FIG. 4 shows an additional implementation with multiple, separatelyexpandable braided assemblies 37, 39. The braided assemblies 37, 39 arespaced from each other along the distal region 32 of retrieval device31. The proximal braided assembly 37 includes braided section 113 thatextends between a fixed attachment point 33 and a slidable collar 115.The distal braided assembly 39 includes braided section 114 that extendsbetween a fixed attachment point 35 and a slidable collar 116. Eachbraided assembly is controlled by a separate activation wire, such thateach braided assembly can be individually controlled. Each activationwire exits the retrieval device 31 from an exit point beneath theindividual braid and attaches to the individual slidable collar (notshown). The multiple activation wires can travel through the same lumenin retrieval device 31, or they could have individual lumens. Dependingupon the positioning of the slidable collars in relation to the fixedattachment points, in some implementations, each additional activationwire can travel through the same lumen and exit the retrieval device atthe same portal, or at different portals. In some implementations, oneor more activation wires can exit from the distal end of the retrievaldevice 31.

As with the previously described implementations, the braids of theimplementation shown in FIG. 4 are formed of a shape memory materialwith a bias toward the collapsed configuration, such that tensioning theactivation wire enables deployment of the braid to a range of diameters.Each braided assembly is deployable to a partially expandedconfiguration by placing a first level of tension in the attachedactivation wire, or to a fully expanded configuration by placing asecond, greater level of tension into the activation wire. Thus, whenmultiple activation wires and braided assemblies are used, a firstbraided assembly can be deployed to a partially expanded state while asecond braided assembly is deployed in a fully expanded state. In somescenarios, it may be advantageous for one braided assembly to be fullycollapsed while another braided assembly is either partially or fullyexpanded. This can be advantageous, for example, when pulling a longerthrombus into the aspiration catheter 106. The proximal braided section113 can be collapsed as it enters the aspiration catheter, prior to thedistal braided section 114 which is still outside of the aspirationcatheter.

In some implementations, braids of separate braided sections or separatebraided assemblies can have different properties, such as differentmaximum expanded diameters, different wire sizes, different wiredensities, different numbers of wires, etc. These properties can varydepending upon the positioning of the braided section or the braidedassembly along the retrieval device. For example, the distal braidedsection or braided assembly might have a larger expanded diameter tobetter pull back against the thrombus, while the proximal braidedsection(s) or braided assembly(s) might be less dense and stronger tobetter engage the middle of the thrombus.

FIGS. 5A-5C show an implementation of the thrombectomy device thatenables use with a guidewire, such that a practitioner can remove andreinsert the device to the same anatomic position multiple times (forexample, to clean the device during the procedure). FIG. 5A showsaspiration catheter 127, retrieval device 121, guidewire tubing 118,braided assembly 123 (in the collapsed configuration), and guidewire 45.Guidewire tubing 118 is positioned around the distal region 61 ofretrieval device 121. The guidewire tubing 118 is shorter than theretrieval device 121 in the longitudinal direction, such that theguidewire 45 leaves the guidewire tubing 118 at the proximal guidewireexit 117 and extends alongside retrieval device in a proximal direction.FIG. 5B shows the implementation of FIG. 5A with the braided assembly123 in an expanded state. As shown in the cross section of FIG. 5C takenat line B—B of FIG. 5B, guidewire 45 extends through the first lumen 124of the guidewire tubing 118. The guidewire 45 exits guidewire tubing 118at distal guidewire exit 47. The guidewire tubing 118 can include adistal atraumatic tip 120. The guidewire tubing 118 can be formed, forexample, of a polymer material. Retrieval device 121, includingactivation wire 125, extends through a second lumen 126 of the guidewiretubing 118. As described above, the activation wire 125 is connected onthe proximal end to a tensioning element, extends through retrievaldevice 121 to an exit point, leaves the retrieval device 121 at the exitpoint (beneath the braid), and attaches at its distal end to theslidable distal collar 122 on the braided assembly 123. The exit pointcan be, for example, a tunnel through the sidewalls of the retrievaldevice 121 and the guidewire tubing 118 (i.e., a tunnel formed by aportal in the sidewall of the retrieval device 121 that isaligned/coaxial with a portal in the sidewall of the guidewire tubing118). In use, the guidewire tubing 118 and the retrieval device 121 areintroduced together over the previously placed vascular guidewire 45.Because the guidewire 45 is retained within the guidewire tubing 118, itis pulled at least partially to the side within the lumen of aspirationcatheter 127 and can move without interfering with activation wire 125.The guidewire tubing 118 and the retrieval device 121 keep theactivation wire 125 and the guidewire 45 moving in an axial direction,independently from one another, using a low-profile and low-frictiondesign. Once in position, the braided assembly 123 is expanded and theproximal end of the aspiration catheter 127 is connected to a vacuumsource. The braided assembly 123 is expanded and then retracted backtoward the aspiration catheter 127, pulling the clot with it andbreaking it into small pieces.

Methods of performing thrombectomy procedures are also disclosed herein.An example method is illustrated in FIGS. 6A-6F. FIG. 6A illustratesthrombus 49 occluding vessel 51. Distal end of aspiration catheter 53 isadvanced through the vasculature to an area proximal to the thrombus 49,as shown in FIG. 6B. The distal end of retrieval device 55 carryingbraided assembly 57 is advanced out the distal end of the aspirationcatheter 53 and through thrombus 49, such that the braided assembly 57is distal to thrombus 49, as shown in FIG. 6C. The practitioner thenplaces tension in the activation wire housed inside the retrieval device55, thereby moving the activation wire longitudinally within the lumenof the retrieval device and moving the slidable collar of the braidedassembly longitudinally over the exterior surface of the retrievaldevice. Movement of the slidable collar via the activation wire causesbraided assembly 57 to expand to the diameter of the practitioner'schoosing. Should the practitioner wish to alter the level of expansionduring the procedure (i.e., change the maximum diameter d of the braidedassembly 57), this is made possible by altering the level of tension inthe activation wire, which again moves the activation wire within theretrieval device and moves the slidable collar, as described above.Advantageously, the distal end of the retrieval device 55 maintains astationary position as the braided assembly is expanded to the optimaldiameter. Maintaining a constant position of the distal end of retrievaldevice 55 is advantageous because sliding proximal/distal movement ofthe distal end within the vessel can result in vessel damage orperforation.

FIG. 6D shows the braided assembly 57 in an expanded configuration,sized to fit the vessel 51. The practitioner then pulls the retrievaldevice 55 proximally and contacts the thrombus 49 with the braidedassembly 57, as shown in FIG. 6E. The thrombus 49 and braided assembly57 are pulled proximally toward aspiration catheter 53. The aspirationcatheter 53 can be connected to an external vacuum source (not shown),which enables the aspiration of the thrombus 49 into the distal end ofthe aspiration catheter 53. The aspiration catheter 53 is then retractedproximally, as illustrated in FIG. 6F, and removed from the body.

The ability to open the braided assembly to a range of differentdiameters is useful to thrombectomy procedures for multiple reasons andin multiple scenarios. The ability to custom fit the braid to aparticular vessel during the procedure is preferable over introducing abraid that expands to a predetermined size, then discoveringmid-procedure that it is either too small to grip the thrombus or thatit is too large and has damaged the vessel. As another exemplaryadvantage, the level of grip between the braid and the thrombus can beoptimized mid-procedure. For example, the practitioner may apply a firstlevel of tension to the activation wire to deploy the braided assemblyto a first expanded outer diameter to contact the thrombus. If the forcebetween the thrombus and the braid is not sufficient to pull thethrombus toward the aspiration catheter, the practitioner can widen thebraid to a second expanded outer diameter by applying a greater secondlevel of tension to the activation wire. This widened diameter increasesthe contact force between the thrombus and the braid, such that thethrombus is more easily pulled toward aspiration catheter.

The methods can also be performed using a guidewire. For example, theguidewire can be positioned distal to the thrombus prior to advancingthe distal end of the retrieval device. The retrieval device extends atleast partially through a lumen of the guidewire tubing, such as in theimplementation of FIGS. 5A-5C. Together, the retrieval device andguidewire tubing are advanced over the guidewire and toward thethrombus. The guidewire extends through a separate lumen of theguidewire tubing than the retrieval device and activation wire. Oncepositioned, the activation wire is moved longitudinally within theretrieval device to expand the braided assembly.

Long thrombi can be addressed using braided assemblies with multiplebraided sections such as the implementation shown in FIG. 3. Movement ofthe slidable collar results in expansion of more than one of the braidedsections, resulting in a relatively long braided assembly. In someimplementations a device with multiple, separately expandable braidedassemblies, such as the one shown in FIG. 4, can be used to treat longthrombi. With separately expandable braided assemblies, as the thrombusis drawn proximally closer to the distal end of the aspiration catheter,the proximally positioned braided assembly collapses from a firstexpanded outer diameter to the collapsed diameter (or to a narrowersecond expanded outer diameter). The distally positioned braidedassembly maintains an expanded outer diameter that is greater than theouter diameter of the proximally positioned braided assembly until ittoo is pulled into the aspiration catheter.

The aspiration systems and methods disclosed herein are configured tocontrol blood loss during thrombus removal. An example aspiration system201 is shown in FIG. 8. The aspiration system 201 includes an aspirationtubing 203, which extends from adapter 204 shown in FIG. 13. Anaspiration lumen 216 extends from (and includes) the lumen of theaspiration catheter 106 and the lumen of the aspiration tubing 203leading to the receptacle 205. The aspiration tubing 203 is coupled to areceptacle 205 for collecting liquid aspirated by the aspirationcatheter 106. In other implementations, aspiration catheter 106 can bedirectly coupled to receptacle 205 for collecting liquid aspirated bythe aspiration catheter 106. The aspiration tubing 203 (or aspirationcatheter 106) creates a fluidic seal with the receptacle 205, and avacuum line 207 is also fluidically coupled to and sealed withreceptacle 205. The vacuum line 207 is fluidically coupled to a vacuumpump 209.

The aspiration tubing 203 is coupled to one or more sensors 211. (Ifaspiration catheter 106 is directly attached to receptacle 205, thesensors 211 are coupled to the catheter 106.) A sensor 211 is configuredto measure a flow parameter associated with a liquid within the lumen ofthe aspiration tubing 203 (such as the flow rate, for example). Thesensor 211 is operably connected to a vacuum controller 213, forexample, via wiring 215 to 4-pin connector 217 (or any suitableconnector). The vacuum controller 213 is also operably coupled to aregulator 219, for example, via wiring 220, and regulator 219 is coupledto vacuum line 207. The regulator 219 is configured to adjust the vacuumpressure within the vacuum line 207.

When the vacuum controller 213 receives the flow parameter from sensor211, it compares the flow parameter to a desired target range and sendsan automatic control signal to the regulator 219, based on thecomparison of the flow parameter to the target range. The automaticcontrol signal causes the regulator 219 to adjust the vacuum pressurewithin vacuum line 207. For example, the automatic control signal cancause the regulator 219 to reduce the vacuum pressure upon adetermination that the flow parameter is above an upper limit of thetarget range, or to decrease the vacuum pressure upon a determinationthat the flow parameter is below a lower limit of the target range. Thevacuum controller 213 and the regulator 219 can optionally communicatein a feedback loop to regulate the vacuum pressure, wherein the vacuumcontroller 213 communicates a control signal to the regulator 219 andthe regulator 219 communicates the current vacuum pressure back to thevacuum controller 213. In one example, communication from the regulator219 to the vacuum controller 213 can be accomplished via wiring 221.These components and operations will be discussed in greater detail,below.

The vacuum pump 209 can be a standard medical suction pumpconventionally used in hospitals, outpatient surgery centers, andclinical practices. As one example, the vacuum pump 209 can be a BasicSuction Pump (Medela AG, Baar, Switzerland), which has piston-cylinderbased drive unit and mechanical overflow to protect the pump. The MedelaBasic Suction pump has a max flow rate of 300 mL/min and a maximumvacuum of 90 kPa below ambient pressure. However, the make or model ofvacuum pump 209 is not limited—it can be any type available in clinicalsettings. The vacuum pump 209 can be provided by the user, or it can beprovided as part of a kit with some or all of the other components shownin FIG. 8.

The aspiration tubing 203 is coupled to the receptacle 205 at an intakeport 223, and the vacuum line 207 is coupled to the receptacle 205 atthe vacuum port 225. The aspiration tubing 203, receptacle 205, andvacuum line 207 can be any make or model. The sizes and materials can beadapted to suit the needs of the particular procedure. These componentscan be provided by the user, or they can be provided as part of a kitwith some or all of the other components shown in FIG. 8. The componentsshown on the right side of the arrows in FIG. 8, including theaspiration tubing 203, the flow sensor 211, the receptacle 205 and thevacuum line 207 can all optionally be disposable to reduce the need forsterilization between procedures. A connector 227 can be placed on thevacuum line 207 to enable connection of the disposal portion 207 a ofthe vacuum line with a reusable portion 207 b of the vacuum line.

As discussed above, regulator 219 communicates with vacuum controller213 to control the pressure in vacuum line 207. In one example, theregulator is an ITC 2090. As one example, the regulator 219 include canhave a valve that opens the vacuum line 207 to the atmosphere, thusdecreasing the vacuum pressure by venting the system. As anotherexample, regulation of flow can be achieved by incorporating anadjustable flow valve, which may widen or narrow the vacuum line 207 bto alter the flow capacity (i.e., direct flow control). Notably,handling flow adjustments on the vacuum side (i.e., to the left of thearrow in FIG. 8) reduces the need to clean the flow handling components.This is an advantage over systems with components that physicallyrestrict blood flow within the aspiration tubing.

The flow sensor 211 can be in direct contact with the liquid in theaspiration tubing 203, or it can be configured for contactless sensing.For example, in some implementations, the flow sensor 211 is apaddle-wheel style sensor positioned within the aspiration lumen 216. Apaddle-wheel style sensor sends turn frequency measurements to thevacuum controller 213, which determines the flow rate accordingly.Alternatively, the flow sensor 211 can be an ultrasonic sensor, alaser-based sensor, an infrared sensor, or some other optical basedsensor, measuring the flow parameters through the walls of aspirationtubing 203 without contacting the blood. These have the benefit of beingreusable, but are typically costlier than a contact-based sensor. Whilea single sensor 211 is shown in FIG. 8, it is further possible toincorporate a plurality of sensors that measure at disparate pointsalong a length of the aspiration tubing 203. In some examples, aninterfacing filter can be positioned upstream from the flow sensor 211to filter clots before they reach the sensor.

Adapter 204 shown in FIG. 13 facilitates the entry of the retrievaldevice 3 through proximal port 206 and into the lumen of the aspirationcatheter 106. Adapter 204 also provides a fluidic coupling between theaspiration catheter 106 and vacuum system 201 (via aspiration tubing203). Infusion port 208 allows for the introduction of saline or otherinfusion fluids. Adapter 204 houses an airtight valve that enablesretrieval device 3 to be introduced through proximal port 206 withoutpassing air into the adapter 204. However, the aspiration tubing 203 caninclude an air leak sensor 214, such as an optical sensor, to detect airpassage in case of valve failure. In some implementations, the air leaksensor 214 is positioned proximal to the flow sensor 211 to detect airbefore it reaches the vacuum system. Alternatively, the air leak sensor214 can be integral with the flow sensor 211.

The air leak sensor 214 can communicate a leak signal to the vacuumcontroller 213, the regulator 219, or directly to the vacuum pump 209,at which point the vacuum controller 213, the regulator 219, or the pump209 slows or stops the vacuum flow while the air leak is addressed,reducing blood loss. In some implementations, there is a leak detectiondelay during initialization of the vacuum. The leak detection delayprevents the aspiration of the initial air in the tube—otherwise, theair leak sensor may detect it as a leak.

As shown in FIG. 8, the flow sensor 211 can be in communication with anindicator 212. The indicator 212 can be configured to inform the user ofa characteristic of the flow parameter or flow rate. For example, theindicator 212 can be an LED light or an LED light panel, with variationsin luminosity or flashing frequency that indicate the flow rate throughthe aspiration tubing 203. The indicator could alternatively be audible,or it could be a display on a user interface 229. The indicator 212 isshown positioned on the flow sensor 211, but in operation could bepositioned anywhere within the system. The flow sensor 211 cancommunicate directly with the indicator 212, or via the vacuumcontroller 213.

The system provide for one or more manual override options, which maycommunicate a complete shut-off of the vacuum or aspiration flow, ascaled diminishing of the vacuum or aspiration flow, a reactivation ofvacuum or aspiration flow, or a scaled increasing of the vacuum oraspiration flow. The manual commands are accepted at one or more manualinputs, such as, but not limited to, clamps, switches, buttons, sliders,knobs, pedals or a digital user interface. In some examples, a clamp 231can be coupled to the aspiration tubing 203 to enable the practitionerto manually stop the flow of blood through the aspiration tubing 203,overriding the automated system. Alternatively or additionally, a manualoverride switch or button can communicate with the regulator 219 tofully open the valve to atmospheric pressure, thereby releasing thepressure in the vacuum line 207. As an alternative to a binary switch orbutton that fully releases the vacuum, sliders, knobs, or the like canbe used to diminish or increase the vacuum force gradually. As anotheralternative, a foot pedal (not shown) can be activated to shut down orslow the flow either at the clamp 231, the regulator 219, or the pump209 (or reactivate and increase the flow at any of those components). Insome implementations, a manual override option can be provided at a userinterface 229 (including manual or digital switches, sliders or knobs).Finally, the user has the option to turn the vacuum on and off at thevacuum pump 209, or gradually adjust its strength.

Triggering a manual override option can induce a first manual controlsignal to be sent from the manual input to the vacuum controller. Thefirst manual control signal can cause the vacuum controller 213 to stopperforming the step of comparing the flow parameter to the target range,or to stop the step of forming the automatic control signal, or to stopthe step of sending the automatic control signal to the regulator. Thevacuum controller 213 can instead send a second manual control signal tothe regulator 219 based on the manual input (information from the firstmanual control signal). Alternatively, triggering a manual overrideoption can send a manual control signal from the manual input directlyto the regulator 219 to raise or lower the vacuum pressure in the vacuumline 207. Likewise, the manual input can be triggered to reactivate anyor all of these processes.

In some implementations, the receptacle 205 can include a receptaclevent 210 in communication with the vacuum controller 213, the vacuumpump 209, the regulator 219, or with one or more of the manual inputs.Any one of the above-listed manual override actions can trigger areceptacle venting signal to be sent to the receptacle vent 210,directly or via the vacuum controller 213. The vent receives thereceptacle venting signal and opens to equilibrate the pressure in thereceptacle 205 with atmospheric pressure. This action eliminatesresidual pressure in the receptacle 205 that might otherwise cause thesuction of additional blood after the manual override action. In someaspects, the venting signal may be a manual control signal sent by thevacuum controller 213 or regulator 219 upon activation of one or moremanual inputs (for example, a manual command to override the vacuumsystem).

The clamp 231 can be coupled to tubing between the aspiration tubing 203and the receptacle 205 and can be activated by a switch 233 for ease ofuse. The switch 233 can have an open configuration and a closedconfiguration. In the closed configuration, the switch tells the clamp231 to close off the flow to the receptacle 205. In the openconfiguration, the switch 233 tells the clamp 231 to open the catheter203 and allow blood to flow into receptacle 205. However, closure ofclamp 231 can cause vacuum pressure to build up in the vacuum line 207.Opening the clamp 231 can thus cause a sudden surge and suction ofblood. To avoid this, the switch 233 can be in operable communicationwith either the vacuum controller 213 or the regulator 219 (for example,via wiring 235). The shifting of switch 233 to the open configurationsends a surge signal to the regulator 219, either directly or via vacuumcontroller 213 as shown in FIG. 8. The surge signal causes the regulatorto decrease the vacuum pressure in vacuum line 207, thereby reducing thesurge of blood associated with opening the clamp 231. In some examples,the switch can be configured to cause a lowering of the vacuum pressurein the vacuum line 207 before releasing the clamp 231.

Some examples of the system include a user interface 229. The userinterface 229 can optionally be a touch screen, or it can be incommunication with a keyboard. Regardless, the user interface can beconfigured to accept manual input. The user interface 229 can be incommunication with the vacuum controller 213 or with the regulator 219,and is configured to send manual control signals to the vacuumcontroller 213 or the regulator 219 responsive to the manual input. Forexample, the user can adjust the upper and lower limits of the targetrange and/or the time delay in triggering a vacuum change (for example,how long the flow rate is permitted to be at or above the upper limitbefore the vacuum pressure is decreased). The user interface can includea manual override button that allows the user to stop automated controland manually set the flow rate through the aspiration tubing 203. Theuser interface 229 can also include readouts to inform the user of theinstantaneous flow rate through the aspiration tubing 203, and/or thetotal blood collected at receptacle 205.

Communication between the components of aspiration system 201 can takeoccur via any suitable communication link that facilitates data exchangebetween the components. Communication links can include wired, wireless,and optical links. Example communication links include, but are notlimited to, a local area network (LAN), a wireless local area network(WLAN), a wide area network (WAN), a metropolitan area network (MAN),Ethernet, the internet, or any other wired, or wireless link such asWiFi, WiMax, 3G, 4G, or 5G. As shown in FIG. 8, the communication linkscan be formed of electrical or optical wires 215, 220, 221, 235, and237. However, the presence of some wires in the drawing is not intendedto indicate that those communication links, or any communication links,within the system must be hard-wired. Any of the communication linksdisclosed herein can be wired or wireless in nature.

The vacuum controller 213 can advantageously be a microprocessor thatoperates independently of a larger computer system. For example, vacuumcontroller 213 can be a complex instruction set microprocessor, areduced instruction set microprocessor, a superscalar processor, anapplication specific integrated circuit, or a digital signalmultiprocessor. The vacuum controller 213 is configured to measurefrequency from the flow parameter received from sensor 211, and includesan analog to digital converter and a digital to analog converter. Powersource 239 can be any suitable power source, and can be external to thevacuum controller 213 (such as a wall outlet) or internal to the vacuumcontroller 213 (such as a battery).

In some implementations, power sensors 240 can be included on the pump209 and/or the vacuum controller 213 in order to synchronize thedelivery of power between the two components. That is, when one of thetwo components (pump 209 or vacuum controller 213) is powered off, thepower sensor 240 on the other of the two components detects the powerchange and is automatically powered off. Likewise, when one of the twocomponents (pump 209 or vacuum controller 213) is powered on, the otheris also automatically powered on.

With the basic structure of the aspiration system 201 being thuslydisclosed, a greater appreciation of the construction and benefits ofmay be gained from the following discussion of the operation of theaspiration system 201 as shown in the flow chart at FIG. 9 and inreference to the diagram of FIG. 8. It is to be noted that thisdiscussion is provided for illustrative purposes only. A method ofcontrolling blood loss during thrombus removal is disclosed herein. Themethod includes first positioning an aspiration tubing 203 within thevascular system of a subject. The vacuum pump 209 is then initialized,or activated (either directly or via power sensor 240 which is incommunication with the power supply to vacuum controller 213). Thevacuum pump 209 is in fluid communication with the aspiration tubing203. The method further includes initiating a flow of blood through anaspiration lumen 216 and measuring a flow parameter of the blood withinthe aspiration lumen 216 using a flow sensor 211. The method furtherincludes receiving the flow parameter from flow sensor 211 at a vacuumcontroller 213. The vacuum controller 213 compares the flow parameter toa target range for the flow parameter and sends an automatic controlsignal to the vacuum regulator 219 based on a comparison of the flowparameter to the target range. The method further includes adjusting thevacuum pressure within the vacuum line 207 according to informationstored in the automatic control signal.

In some example methods, activating a vacuum pump comprises activatingthe vacuum pump at full power, as shown in FIG. 9. Full vacuum power isfed to the regulator 219, which is regulated by the vacuum controller213. When the flow exceeds the upper limit, the vacuum pump can bedropped off full power, and a finer level of intermediate control can becommanded via the regulator. The regulator can vent the system toatmospheric pressure to the extent necessary to accomplish the desiredintermediate vacuum level.

The vacuum is imposed on the catheter 203 through the receptacle 205.The catheter 203 draws fluid from the patient. The flow is measured anda closed circuit loop is formed that provides controlling the desiredflow with the amount of vacuum. When the flow drops below the lowerlimit, the vacuum controller 213 returns the vacuum pump 209 to fullpower and commands the regulator to fully close the system toatmospheric pressure.

For example, FIG. 10 shows a line graph of the flow rate in aspirationtubing 203. At initialization, the vacuum is increased to full power andflow rate reaches the first peak seen on the graph—the upper limit(uppermost dashed horizontal line). The vacuum controller 213 determinesthat the upper limit of the flow rate has been reached, and controllertells the regulator 219 to reduce the pressure in the vacuum line 207.The vacuum controller 213 continues to tell the regulator 219 to reducevacuum pressure until the flow rate reaches the intermediate level(middle horizontal dashed peak). The flow rate continues at theintermediate level until it is reduced by the presence of a clot. Thereduction of flow rate down to the lower limit (lowermost dashedhorizontal line) causes the vacuum controller 213 to tell the regulator219 to enable allow full vacuum power in the vacuum line 207, and theflow rate again reaches the upper limit.

Adjusting the vacuum pressure can be accomplished by decreasing thevacuum pressure upon a determination that the flow parameter is above anupper limit of the target range. In some examples, the upper limit is aflow rate of from 70 mL per minute to 130 mL per minute (including, forexample, 70 mL per minute, 75 mL per minute, 80 mL per minute, 85 mL perminute, 90 mL per minute, 95 mL per minute, 100 mL per minute, 105 mLper minute, 110 mL per minute, 115 mL per minute, 120 mL per minute, 125mL per minute, and 130 mL per minute).

In some example methods, the vacuum pressure is decreased until themeasured flow parameter reaches an intermediate level flow rate of from20 mL per minute to 50 mL per minute (including, for example, 20 mL perminute, 25 mL per minute, 30 mL per minute, 35 mL per minute, 40 mL perminute, 45 mL per minute, and 50 mL per minute).

Adjusting the vacuum pressure can be accomplished by increasing thevacuum pressure upon a determination that the flow parameter is below alower limit of the target range. The lower limit can be, for example,from 0 mL per minute to 50 mL per minute (including, for example, 0 mLper minute, 10 mL per minute, 15 mL per minute, 20 mL per minute, 25 mLper minute, 30 mL per minute, 35 mL per minute, 40 mL per minute, 45 mLper minute, and 50 mL per minute).

In some implementations, decreasing or increasing the vacuum pressurecan occur gradually, or in a stepwise manner, according to an aspirationprogram. This helps to reduce sudden surges and stops, giving thepractitioner sufficient time to respond as necessary to sudden changesin flow rate. For example, FIG. 11, shows a line graph where flow rateis decreased in a step wise manner. At initialization, the vacuum isincreased to full power and flow rate reaches the first peak seen on thegraph—the upper limit of 100 mL per minute in this example (uppermostdashed horizontal line). The vacuum controller 213 determines that theupper limit of the flow rate has been reached, and vacuum controller 213tells the regulator 219 to reduce the pressure in the vacuum line 207 toa first intermediate flow rate of 75 mL per minute (in this example).The vacuum controller 213 operates the regulator 219 at this firstintermediate level for a specified time period and then tells theregulator to decrease the flow rate to a second intermediate level-50 mLper minute in this example. The vacuum controller 213 operates theregulator at this second intermediate level for a specified time periodand then tells the regulator to decrease the flow rate to a thirdintermediate level-20 mL per minute in this example. The flow ratecontinues at the third intermediate level until it is reduced by thepresence of a clot. The reduction of flow rate down to the lower limit(lowermost dashed horizontal line-5 mL per minute in this example)causes the vacuum controller 213 to tell the regulator 219 to enableallow full vacuum power in the vacuum line 207, and the flow rate againreaches the upper limit.

In some implementations, the durations of time in each of the steps ofthe aspiration program shown in FIG. 11 can be programmable via a manualinput such as those described above. The user can set the duration ofthe “burst” (full vacuum power) and of each stepwise interval via aslider, a knob, a user interface, the software, or a combinationthereof. The user can thus tailor the aspiration program to theprocedural situation.

It should be appreciated that the logical operations described hereinwith respect to the various figures may be implemented (1) as a sequenceof computer implemented acts or program modules (i.e., software) runningon a computing device (e.g., the computing device described in FIG. 12),(2) as interconnected machine logic circuits or circuit modules (i.e.,hardware) within the computing device and/or (3) a combination ofsoftware and hardware of the computing device. Thus, the logicaloperations discussed herein are not limited to any specific combinationof hardware and software. The implementation is a matter of choicedependent on the performance and other requirements of the computingdevice. Accordingly, the logical operations described herein arereferred to variously as operations, structural devices, acts, ormodules. These operations, structural devices, acts and modules may beimplemented in software, in firmware, in special purpose digital logic,and any combination thereof. It should also be appreciated that more orfewer operations may be performed than shown in the figures anddescribed herein. These operations may also be performed in a differentorder than those described herein.

Referring to FIG. 12, an example computing device 900 upon whichimplementations of the invention may be implemented is illustrated. Forexample, the vacuum controller 213 may each be implemented as acomputing device, such as computing device 900. It should be understoodthat the example computing device 900 is only one example of a suitablecomputing environment upon which implementations of the invention may beimplemented. Optionally, the computing device 900 can be a well-knowncomputing system including, but not limited to, personal computers,servers, handheld or laptop devices, multiprocessor systems,microprocessor-based systems, network personal computers (PCs),minicomputers, mainframe computers, embedded systems, and/or distributedcomputing environments including a plurality of any of the above systemsor devices. Distributed computing environments enable remote computingdevices, which are connected to a communication network or other datatransmission medium, to perform various tasks. In the distributedcomputing environment, the program modules, applications, and other datamay be stored on local and/or remote computer storage media.

In an implementation, the computing device 900 may comprise two or morecomputers in communication with each other that collaborate to perform atask. For example, but not by way of limitation, an application may bepartitioned in such a way as to permit concurrent and/or parallelprocessing of the instructions of the application. Alternatively, thedata processed by the application may be partitioned in such a way as topermit concurrent and/or parallel processing of different portions of adata set by the two or more computers. In an implementation,virtualization software may be employed by the computing device 900 toprovide the functionality of a number of servers that is not directlybound to the number of computers in the computing device 900. Forexample, virtualization software may provide twenty virtual servers onfour physical computers. In an implementation, the functionalitydisclosed above may be provided by executing the application and/orapplications in a cloud computing environment. Cloud computing maycomprise providing computing services via a network connection usingdynamically scalable computing resources. Cloud computing may besupported, at least in part, by virtualization software. A cloudcomputing environment may be established by an enterprise and/or may behired on an as-needed basis from a third party provider. Some cloudcomputing environments may comprise cloud computing resources owned andoperated by the enterprise as well as cloud computing resources hiredand/or leased from a third party provider.

In its most basic configuration, computing device 900 typically includesat least one processing unit 920 and system memory 930. Depending on theexact configuration and type of computing device, system memory 930 maybe volatile (such as random access memory (RAM)), non-volatile (such asread-only memory (ROM), flash memory, etc.), or some combination of thetwo. This most basic configuration is illustrated in FIG. 12 by dashedline 910. The processing unit 920 may be a standard programmableprocessor that performs arithmetic and logic operations necessary foroperation of the computing device 900. While only one processing unit920 is shown, multiple processors may be present. Thus, whileinstructions may be discussed as executed by a processor, theinstructions may be executed simultaneously, serially, or otherwiseexecuted by one or multiple processors. The computing device 900 mayalso include a bus or other communication mechanism for communicatinginformation among various components of the computing device 900.

Computing device 900 may have additional features/functionality. Forexample, computing device 900 may include additional storage such asremovable storage 940 and non-removable storage 950 including, but notlimited to, magnetic or optical disks or tapes. Computing device 900 mayalso contain network connection(s) 980 that allow the device tocommunicate with other devices such as over the communication pathwaysdescribed herein. The network connection(s) 980 may take the form ofmodems, modem banks, Ethernet cards, universal serial bus (USB)interface cards, serial interfaces, token ring cards, fiber distributeddata interface (FDDI) cards, wireless local area network (WLAN) cards,radio transceiver cards such as code division multiple access (CDMA),global system for mobile communications (GSM), long-term evolution(LTE), worldwide interoperability for microwave access (WiMAX), and/orother air interface protocol radio transceiver cards, and otherwell-known network devices. Computing device 900 may also have inputdevice(s) 970 such as a keyboards, keypads, switches, dials, mice, trackballs, touch screens, voice recognizers, card readers, paper tapereaders, or other well-known input devices. Output device(s) 960 such asa printers, video monitors, liquid crystal displays (LCDs), touch screendisplays, displays, speakers, etc. may also be included. The additionaldevices may be connected to the bus in order to facilitate communicationof data among the components of the computing device 900. All thesedevices are well known in the art and need not be discussed at lengthhere.

The processing unit 920 may be configured to execute program codeencoded in tangible, computer-readable media. Tangible,computer-readable media refers to any media that is capable of providingdata that causes the computing device 900 (i.e., a machine) to operatein a particular fashion. Various computer-readable media may be utilizedto provide instructions to the processing unit 920 for execution.Example tangible, computer-readable media may include, but is notlimited to, volatile media, non-volatile media, removable media andnon-removable media implemented in any method or technology for storageof information such as computer readable instructions, data structures,program modules or other data. System memory 930, removable storage 940,and non-removable storage 950 are all examples of tangible, computerstorage media. Example tangible, computer-readable recording mediainclude, but are not limited to, an integrated circuit (e.g.,field-programmable gate array or application-specific IC), a hard disk,an optical disk, a magneto-optical disk, a floppy disk, a magnetic tape,a holographic storage medium, a solid-state device, RAM, ROM,electrically erasable program read-only memory (EEPROM), flash memory orother memory technology, CD-ROM, digital versatile disks (DVD) or otheroptical storage, magnetic cassettes, magnetic tape, magnetic diskstorage or other magnetic storage devices.

It is fundamental to the electrical engineering and software engineeringarts that functionality that can be implemented by loading executablesoftware into a computer can be converted to a hardware implementationby well-known design rules. Decisions between implementing a concept insoftware versus hardware typically hinge on considerations of stabilityof the design and numbers of units to be produced rather than any issuesinvolved in translating from the software domain to the hardware domainGenerally, a design that is still subject to frequent change may bepreferred to be implemented in software, because re-spinning a hardwareimplementation is more expensive than re-spinning a software design.Generally, a design that is stable that will be produced in large volumemay be preferred to be implemented in hardware, for example in anapplication specific integrated circuit (ASIC), because for largeproduction runs the hardware implementation may be less expensive thanthe software implementation. Often a design may be developed and testedin a software form and later transformed, by well-known design rules, toan equivalent hardware implementation in an application specificintegrated circuit that hardwires the instructions of the software. Inthe same manner as a machine controlled by a new ASIC is a particularmachine or apparatus, likewise a computer that has been programmedand/or loaded with executable instructions may be viewed as a particularmachine or apparatus.

In an example implementation, the processing unit 920 may executeprogram code stored in the system memory 930. For example, the bus maycarry data to the system memory 930, from which the processing unit 920receives and executes instructions. The data received by the systemmemory 930 may optionally be stored on the removable storage 940 or thenon-removable storage 950 before or after execution by the processingunit 920.

It should be understood that the various techniques described herein maybe implemented in connection with hardware or software or, whereappropriate, with a combination thereof. Thus, the methods andapparatuses of the presently disclosed subject matter, or certainaspects or portions thereof, may take the form of program code (i.e.,instructions) embodied in tangible media, such as floppy diskettes,CD-ROMs, hard drives, or any other machine-readable storage mediumwherein, when the program code is loaded into and executed by a machine,such as a computing device, the machine becomes an apparatus forpracticing the presently disclosed subject matter. In the case ofprogram code execution on programmable computers, the computing devicegenerally includes a processor, a storage medium readable by theprocessor (including volatile and non-volatile memory and/or storageelements), at least one input device, and at least one output device.One or more programs may implement or utilize the processes described inconnection with the presently disclosed subject matter, e.g., throughthe use of an application programming interface (API), reusablecontrols, or the like. Such programs may be implemented in a high levelprocedural or object-oriented programming language to communicate with acomputer system. However, the program(s) can be implemented in assemblyor machine language, if desired. In any case, the language may be acompiled or interpreted language and it may be combined with hardwareimplementations.

Implementations of the methods and systems may be described herein withreference to block diagrams and flowchart illustrations of methods,systems, apparatuses and computer program products. It will beunderstood that each block of the block diagrams and flowchartillustrations, and combinations of blocks in the block diagrams andflowchart illustrations, respectively, can be implemented by computerprogram instructions. These computer program instructions may be loadedonto a general purpose computer, special purpose computer, or otherprogrammable data processing apparatus to produce a machine, such thatthe instructions which execute on the computer or other programmabledata processing apparatus create a means for implementing the functionsspecified in the flowchart block or blocks.

These computer program instructions may also be stored in acomputer-readable memory that can direct a computer or otherprogrammable data processing apparatus to function in a particularmanner, such that the instructions stored in the computer-readablememory produce an article of manufacture including computer-readableinstructions for implementing the function specified in the flowchartblock or blocks. The computer program instructions may also be loadedonto a computer or other programmable data processing apparatus to causea series of operational steps to be performed on the computer or otherprogrammable apparatus to produce a computer-implemented process suchthat the instructions that execute on the computer or other programmableapparatus provide steps for implementing the functions specified in theflowchart block or blocks.

Accordingly, blocks of the block diagrams and flowchart illustrationssupport combinations of means for performing the specified functions,combinations of steps for performing the specified functions and programinstruction means for performing the specified functions. It will alsobe understood that each block of the block diagrams and flowchartillustrations, and combinations of blocks in the block diagrams andflowchart illustrations, can be implemented by special purposehardware-based computer systems that perform the specified functions orsteps, or combinations of special purpose hardware and computerinstructions.

Example

Conventional aspiration systems operate with the vacuum being controlledwith a “foot valve” by the operating physician. This is not very preciseand is a distraction to the primary job of guiding the catheter. Theprinciple of this system is to automate the process. The reader isdirected to the flow chart of FIG. 9 for reference.

The system is controlled by a microprocessor controller (MC). A simpledevice as compared to a conventional computer and can run “stand alone”.That means all it needs to run is powering it up. The program is writtento be failsafe and straightforward. On power up the MC initializes andperforms a test of the system and a checksum on the program. Any problemwith this stops the process. The system uses a Vacuum Regulator (VR)module. It takes raw unregulated vacuum from a user supplied vacuum pump(VP). The VR can be set to deliver from full to almost zero vacuum buythe MC while the VP is set to maximum vacuum.

Another component of the system is the Flow Sensor (FS). This devicemeasures the amount of blood flow out of the catheter. There are severalavailable technologies for the sensor. The most straight forward andinexpensive is the impeller rotational sensor. It measures the flow byhow fast an impeller spins.

An ultrasonic flow sensor works well in this application and canaccurately measure the low flow rates that might indicate thepossibility of a blockage caused by a blood. A small tube from thecatheter is placed in a cavity on the sensor and the velocity of theflow is determined. An electrical pulse train is produced that has afrequency proportional to the flow rate that is read by the MC. Thesensor is completely isolated from any liquids and can be usedrepeatedly, where as the rotational sensor would have to be disposed ofafter every procedure.

In this example, 100 mL/minute is the upper limit on the flow rate.After power on test is complete, the VR commands full vacuum. The flowcan reach 100 mL/min quickly, and the MC detects that and quicklycommands the VR to reduce vacuum and to control the flow by adjustingthe vacuum to a midline flow rate of around 30 mL/min Without the VR,blood flow out of the catheter would be excessive.

The flow rate from 100 mL/min to 30 mL/min can be achieved in steps sothat the clinician gets enough time to make necessary decisions/actions.Same delay time or stepped approach is taken for the application of fullvacuum to the aspiration tubing when the flow rate falls below a lowerlimit of 10 ml/min (or the tip of the catheter engages a clot, inpractice).

If, while the system is regulating to 30 mL/min, it drops below 10mL/min, a blockage of the catheter has probably occurred. The systemwill attempt to “Clear” the blockage, usually caused by encountering ablood clot, by commanding full vacuum power from the VR. As in thebeginning, when the flow hits 100 mL/min, the MC will command the VRwill scale back and regulate to 30 mL/min.

The cycle repeats until the unit is shut off. Before complete shutdown,the MC commands the VR to completely release the vacuum.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present invention has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the invention in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the invention. Theimplementation was chosen and described in order to best explain theprinciples of the invention and the practical application, and to enableothers of ordinary skill in the art to understand the invention forvarious implementations with various modifications as are suited to theparticular use contemplated.

What is claimed is:
 1. An aspiration system for controlling blood lossduring thrombus removal, the aspiration system comprising: an aspirationcatheter; a thrombus retrieval device configured to extend through theaspiration catheter; an aspiration tubing fluidically coupled to theaspiration catheter; an aspiration lumen extending through theaspiration catheter and the aspiration tubing; a sensor configured tomeasure a flow parameter associated with a liquid within the aspirationlumen; a receptacle configured to collect liquid aspirated by theaspiration catheter; a vacuum line fluidically coupled to thereceptacle; a regulator configured to adjust a vacuum pressure withinthe vacuum line; and a vacuum controller operably coupled to the sensorand the regulator, the vacuum controller configured to: receive the flowparameter from the sensor; compare the flow parameter to a target rangefor the flow parameter; and send an automatic control signal to theregulator based on a comparison of the flow parameter to the targetrange; wherein the automatic control signal causes the regulator toadjust the vacuum pressure within the vacuum line; and wherein theautomatic control signal causes the regulator to decrease the vacuumpressure upon a determination that the flow parameter is above an upperlimit of the target range, and wherein the automatic control signalcauses the regulator to increase the vacuum pressure upon adetermination that the flow parameter is below a lower limit of thetarget range.
 2. The aspiration system of claim 1, wherein the upperlimit is a flow rate from 70 mL per minute to 130 mL per minute.
 3. Theaspiration system of claim 1, wherein the lower limit is a flow ratefrom 0 mL per minute to 40 mL per minute.
 4. The aspiration system ofclaim 1, wherein the vacuum controller is configured to adjust the flowrate to an intermediate level, and wherein the intermediate level is aflow rate from 20 mL per minute to 50 mL per minute.
 5. The aspirationsystem of claim 1, wherein increases in vacuum pressure and decreases invacuum pressure occur in a stepwise manner.
 6. The aspiration system ofclaim 1, wherein the vacuum controller is configured to activate anaspiration program, increasing and decreasing vacuum pressure in astepwise manner, upon receipt of information from one or more manualinputs in communication with the regulator, the vacuum controller, orboth.
 7. The aspiration system of claim 1, further comprising aplurality of sensors configured to measure one or more parametersassociated with fluid flow in the aspiration lumen at disparate pointsalong a length of the aspiration lumen and to send measured parametersto the vacuum controller.
 8. The aspiration system of claim 1, whereinthe flow parameter is a flow rate.
 9. The aspiration system of claim 1,further comprising an air leak sensor in communication with the vacuumcontroller or the regulator, the air leak sensor configured to detectair flow through the aspiration tubing and to send a leak signal to thevacuum controller, the regulator, or the vacuum pump upon detection ofair through the aspiration tubing.
 10. The aspiration system of claim 9,wherein the vacuum controller, the regulator, or the pump are configuredto slow or stop the vacuum flow while the air leak is addressed.
 11. Theaspiration system of claim 10, wherein the vacuum controller isconfigured to delay detection of air leaks or to delay controlling thevacuum in response to detection of air leaks during an initializationperiod.
 12. The aspiration system of claim 1, further comprising a powersensor configured to synchronize the delivery of power between the pumpand the vacuum controller.
 13. The aspiration system of claim 1, whereinthe vacuum controller is a microprocessor controller.
 14. The aspirationsystem of claim 1, wherein the vacuum controller comprises an analog todigital converter and a digital to analog converter.
 15. The aspirationsystem of claim 1, wherein the vacuum controller is configured tomeasure a frequency from the flow parameter.
 16. The aspiration systemof claim 1, further comprising a manual input in communication with oneor more of the vacuum controller, the regulator, and a receptacle vent,wherein the manual input is configured to accept a manual command andsend a first manual control signal responsive to the manual command toone or more of the vacuum controller, the regulator, and the receptaclevent.
 17. The aspiration system of claim 16, wherein, upon receipt ofthe first manual control signal, the vacuum controller is configured tostop one or more steps of comparing the flow parameter to a target rangefor the flow parameter, forming an automatic control signal, and sendingthe automatic control signal to the regulator.
 18. The aspiration systemof claim 16, wherein the vacuum controller is configured to send asecond manual control signal to the regulator, the receptacle vent, orboth based on the first manual control signal.
 19. The aspiration systemof claim 18, wherein the regulator controls the vacuum pressure withinthe vacuum line upon receipt of the first manual control signal or thesecond manual control signal.
 20. The aspiration system of claim 18,wherein the receptacle vent opens or shuts upon receipt of the firstmanual control signal or the second manual control signal.
 21. Theaspiration system of claim 1, wherein the aspiration system furthercomprises a clamp coupled to the aspiration tubing and a switch operablycoupled to the clamp, the switch comprising a closed configuration andan open configuration, wherein the switch in the closed configurationcauses the clamp to stop fluid flow through the aspiration tubing, andwherein the switch in the open configuration causes the clamp to allowfluid flow through the aspiration tubing.
 22. The aspiration system ofclaim 21, wherein the switch is in communication with the vacuumcontroller and/or the regulator, and shifting the switch to the openconfiguration sends a surge protection signal to the regulator and/or tothe vacuum controller, and wherein upon receipt of the surge protectionsignal, the regulator and/or the vacuum controller is configured toreduce the vacuum pressure.